Here is a generic solution as requested:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:param name="pLeafNodes" select="//Level-4"/>
<xsl:template match="https://stackoverflow.com/">
<t>
<xsl:call-template name="StructRepro"/>
</t>
</xsl:template>
<xsl:template name="StructRepro">
<xsl:param name="pLeaves" select="$pLeafNodes"/>
<xsl:for-each select="$pLeaves">
<xsl:apply-templates mode="build" select="/*">
<xsl:with-param name="pChild" select="."/>
<xsl:with-param name="pLeaves" select="$pLeaves"/>
</xsl:apply-templates>
</xsl:for-each>
</xsl:template>
<xsl:template mode="build" match="node()|@*">
<xsl:param name="pChild"/>
<xsl:param name="pLeaves"/>
<xsl:copy>
<xsl:apply-templates mode="build" select="@*"/>
<xsl:variable name="vLeafChild" select=
"*[count(.|$pChild) = count($pChild)]"/>
<xsl:choose>
<xsl:when test="$vLeafChild">
<xsl:apply-templates mode="build"
select="$vLeafChild
|
node()[not(count(.|$pLeaves) = count($pLeaves))]">
<xsl:with-param name="pChild" select="$pChild"/>
<xsl:with-param name="pLeaves" select="$pLeaves"/>
</xsl:apply-templates>
</xsl:when>
<xsl:otherwise>
<xsl:apply-templates mode="build" select=
"node()[not(.//*[count(.|$pLeaves) = count($pLeaves)])
or
.//*[count(.|$pChild) = count($pChild)]
]
">
<xsl:with-param name="pChild" select="$pChild"/>
<xsl:with-param name="pLeaves" select="$pLeaves"/>
</xsl:apply-templates>
</xsl:otherwise>
</xsl:choose>
</xsl:copy>
</xsl:template>
<xsl:template match="text()"/>
</xsl:stylesheet>
When applied on the provided simplified (and generic) XML document:
<Level-1>
...
<Level-2>
...
<Level-3>
...
<Level-4>A</Level-4>
<Level-4>B</Level-4>
...
</Level-3>
...
</Level-2>
...
</Level-1>
the wanted, correct result is produced:
<Level-1>
...
<Level-2>
...
<Level-3>
<Level-4>A</Level-4>
</Level-3>
...
</Level-2>
...
</Level-1>
<Level-1>
...
<Level-2>
...
<Level-3>
<Level-4>B</Level-4>
</Level-3>
...
</Level-2>
...
</Level-1>
Now, if we change the line:
<xsl:param name="pLeafNodes" select="//Level-4"/>
to:
<xsl:param name="pLeafNodes" select="//Job"/>
and apply the transformation to the Employee XML document:
<Employee name="A Name">
<Address>123 A Street</Address>
<Age>28</Age>
<EmploymentHistory>
<Employment country="US">
<Comment>List of previous jobs in the US</Comment>
<Jobs>3</Jobs>
<JobDetails>
<Job title = "Senior Developer">
<StartDate>01/10/2001</StartDate>
<Months>38</Months>
</Job>
<Job title = "Senior Developer">
<StartDate>01/12/2004</StartDate>
<Months>6</Months>
</Job>
<Job title = "Senior Developer">
<StartDate>01/06/2005</StartDate>
<Months>10</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<EmploymentHistory>
<Employment country="UK">
<Comment>List of previous jobs in the UK</Comment>
<Jobs>2</Jobs>
<JobDetails>
<Job title = "Junior Developer">
<StartDate>01/05/1999</StartDate>
<Months>25</Months>
</Job>
<Job title = "Junior Developer">
<StartDate>01/07/2001</StartDate>
<Months>3</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<Available>true</Available>
<Experience unit="years">6</Experience>
</Employee>
we again get the wanted, correct result:
<t>
<Employee name="A Name">
<Address>123 A Street</Address>
<Age>28</Age>
<EmploymentHistory>
<Employment country="US">
<Comment>List of previous jobs in the US</Comment>
<Jobs>3</Jobs>
<JobDetails>
<Job title="Senior Developer">
<StartDate>01/10/2001</StartDate>
<Months>38</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<Available>true</Available>
<Experience unit="years">6</Experience>
</Employee>
<Employee name="A Name">
<Address>123 A Street</Address>
<Age>28</Age>
<EmploymentHistory>
<Employment country="US">
<Comment>List of previous jobs in the US</Comment>
<Jobs>3</Jobs>
<JobDetails>
<Job title="Senior Developer">
<StartDate>01/12/2004</StartDate>
<Months>6</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<Available>true</Available>
<Experience unit="years">6</Experience>
</Employee>
<Employee name="A Name">
<Address>123 A Street</Address>
<Age>28</Age>
<EmploymentHistory>
<Employment country="US">
<Comment>List of previous jobs in the US</Comment>
<Jobs>3</Jobs>
<JobDetails>
<Job title="Senior Developer">
<StartDate>01/06/2005</StartDate>
<Months>10</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<Available>true</Available>
<Experience unit="years">6</Experience>
</Employee>
<Employee name="A Name">
<Address>123 A Street</Address>
<Age>28</Age>
<EmploymentHistory>
<Employment country="UK">
<Comment>List of previous jobs in the UK</Comment>
<Jobs>2</Jobs>
<JobDetails>
<Job title="Junior Developer">
<StartDate>01/05/1999</StartDate>
<Months>25</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<Available>true</Available>
<Experience unit="years">6</Experience>
</Employee>
<Employee name="A Name">
<Address>123 A Street</Address>
<Age>28</Age>
<EmploymentHistory>
<Employment country="UK">
<Comment>List of previous jobs in the UK</Comment>
<Jobs>2</Jobs>
<JobDetails>
<Job title="Junior Developer">
<StartDate>01/07/2001</StartDate>
<Months>3</Months>
</Job>
</JobDetails>
</Employment>
</EmploymentHistory>
<Available>true</Available>
<Experience unit="years">6</Experience>
</Employee>
</t>
Explanation: The processing is done in a named template (StructRepro) and controlled by a single external parameter named pLeafNodes, that must contain a nodeset of all nodes whose “upward structure” is to be reproduced in the result.